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This is not an exhaustive list.</p> 95<h3>Multiple Targets</h3> 96<p>It needs to be possible to build the Android platform for multiple targets. 97This means:</p> 98<ul> 99 <li>The build system will support building tools for the host platform, 100 both ones that are used in the build process itself, and developer tools 101 like the simulator.</li> 102 <li>The build system will need to be able to build tools on Linux 103 (definitely Goobuntu and maybe Grhat), MacOS, and to some degree on 104 Windows.</li> 105 <li>The build system will need to be able to build the OS on Linux, and in 106 the short-term, MacOS. Note that this is a conscious decision to stop 107 building the OS on Windows. We are going to rely on the emulator there 108 and not attempt to use the simulator. This is a requirement change now 109 that the emulator story is looking brighter.</li> 110</ul> 111<h3>Non-Recursive Make</h3> 112<p>To achieve the objectives, the build system will be rewritten to use make 113non-recursively. For more background on this, read <a href="http://aegis.sourceforge.net/auug97.pdf">Recursive Make Considered Harmful</a>. For those that don't 114want PDF, here is the 115<a href="http://72.14.203.104/search?q=cache:HwuX7YF2uBIJ:aegis.sourceforge.net/auug97.pdf&hl=en&gl=us&ct=clnk&cd=2&client=firefox">Google translated version</a>. 116<h3>Rapid Compile-Test Cycles</h3> 117<p>When developing a component, for example a C++ shared library, it must be 118possible to easily rebuild just that component, and not have to wait more than a 119couple seconds for dependency checks, and not have to wait for unneeded 120components to be built.</p> 121<h3>Both Environment and Config File Based Settings</h3> 122<p>To set the target, and other options, some people on the team like to have a 123configuration file in a directory so they do not have an environment setup 124script to run, and others want an environment setup script to run so they can 125run builds in different terminals on the same tree, or switch back and forth 126in one terminal. We will support both.</p> 127<h3>Object File Directory / make clean</h3> 128<p>Object files and other intermediate files will be generated into a directory 129that is separate from the source tree. The goal is to have make clean be 130"rm -rf <obj>" in the tree root directory. The primary goals of 131this are to simplify searching the source tree, and to make "make clean" more 132reliable.</p> 133 134<h3>SDK</h3> 135<p>The SDK will be a tarball that will allow non-OS-developers to write apps. 136The apps will actually be built by first building the SDK, and then building 137the apps against that SDK. This will hopefully (1) make writing apps easier 138for us, because we won't have to rebuild the OS as much, and we can use the 139standard java-app development tools, and (2) allow us to dog-food the SDK, to 140help ensure its quality. Cedric has suggested (and I agree) that apps built 141from the SDK should be built with ant. Stay tuned for more details as we 142figure out exactly how this will work.</p> 143 144<h3>Dependecies</h3> 145<p>Dependencies should all be automatic. Unless there is a custom tool involved 146(e.g. the webkit has several), the dependencies for shared and static libraries, 147.c, .cpp, .h, .java, java libraries, etc., should all work without intervention 148in the Android.mk file.</p> 149 150<h3>Hiding command lines</h3> 151<p>The default of the build system will be to hide the command lines being 152executed for make steps. It will be possible to override this by specifying 153the showcommands pseudo-target, and possibly by setting an environment 154variable.</p> 155 156<h3>Wildcard source files</h3> 157<p>Wildcarding source file will be discouraged. It may be useful in some 158scenarios. The default <code>$(wildcard *)</code> will not work due to the 159current directory being set to the root of the build tree.<p> 160 161<h3>Multiple targets in one directory</h3> 162<p>It will be possible to generate more than one target from a given 163subdirectory. For example, libutils generates a shared library for the target 164and a static library for the host.</p> 165 166<h3>Makefile fragments for modules</h3> 167<p><b>Android.mk</b> is the standard name for the makefile fragments that 168control the building of a given module. Only the top directory should 169have a file named "Makefile".</p> 170 171<h3>Use shared libraries</h3> 172<p>Currently, the simulator is not built to use shared libraries. This should 173be fixed, and now is a good time to do it. This implies getting shared 174libraries to work on Mac OS.</p> 175 176 177<h2>Nice to Have</h2> 178 179<p>These things would be nice to have, and this is a good place to record them, 180however these are not promises.</p> 181 182<h3>Simultaneous Builds</h3> 183<p>The hope is to be able to do two builds for different combos in the same 184tree at the same time, but this is a stretch goal, not a requirement. 185Doing two builds in the same tree, not at the same time must work. (update: 186it's looking like we'll get the two builds at the same time working)</p> 187 188<h3>Deleting headers (or other dependecies)</h3> 189<p>Problems can arise if you delete a header file that is referenced in 190".d" files. The easy way to deal with this is "make clean". There 191should be a better way to handle it. (from fadden)</p> 192<p>One way of solving this is introducing a dependency on the directory. The 193problem is that this can create extra dependecies and slow down the build. 194It's a tradeoff.</p> 195 196<h3>Multiple builds</h3> 197<p>General way to perform builds across the set of known platforms. This 198would make it easy to perform multiple platform builds when testing a 199change, and allow a wide-scale "make clean". Right now the buildspec.mk 200or environment variables need to be updated before each build. (from fadden)</p> 201 202<h3>Aftermarket Locales and Carrier</h3> 203<p>We will eventually need to add support for creating locales and carrier 204customizations to the SDK, but that will not be addressed right now.</p> 205 206 207<h2><a id="usage"/>Usage</h2> 208<p>You've read (or scrolled past) all of the motivations for this build system, 209and you want to know how to use it. This is the place.</p> 210 211<h3>Your first build</h3> 212<p>The <a href="../building.html">Building</a> document describes how do do 213builds.</p> 214 215<h3>build/envsetup.sh functions</h3> 216If you source the file build/envsetup.sh into your bash environment, 217<code>. build/envsetup.sh</code>you'll get a few helpful shell functions: 218 219<ul> 220<li><b>printconfig</b> - Prints the current configuration as set by the 221lunch and choosecombo commands.</li> 222<li><b>m</b> - Runs <code>make</code> from the top of the tree. This is 223useful because you can run make from within subdirectories. If you have the 224<code>TOP</code> environment variable set, it uses that. If you don't, it looks 225up the tree from the current directory, trying to find the top of the tree.</li> 226<li><b>croot</b> - <code>cd</code> to the top of the tree.</li> 227<li><b>sgrep</b> - grep for the regex you provide in all .c, .cpp, .h, .java, 228and .xml files below the current directory.</li> 229</ul> 230 231<h3>Build flavors/types</h3> 232<p> 233When building for a particular product, it's often useful to have minor 234variations on what is ultimately the final release build. These are the 235currently-defined "flavors" or "types" (we need to settle on a real name 236for these). 237</p> 238 239<table border=1> 240<tr> 241 <td> 242 <code>eng<code> 243 </td> 244 <td> 245 This is the default flavor. A plain "<code>make</code>" is the 246 same as "<code>make eng</code>". <code>droid</code> is an alias 247 for <code>eng</code>. 248 <ul> 249 <li>Installs modules tagged with: <code>eng</code>, <code>debug</code>, 250 <code>user</code>, and/or <code>development</code>. 251 <li>Installs non-APK modules that have no tags specified. 252 <li>Installs APKs according to the product definition files, in 253 addition to tagged APKs. 254 <li><code>ro.secure=0</code> 255 <li><code>ro.debuggable=1</code> 256 <li><code>ro.kernel.android.checkjni=1</code> 257 <li><code>adb</code> is enabled by default. 258 </td> 259</tr> 260<tr> 261 <td> 262 <code>user<code> 263 </td> 264 <td> 265 "<code>make user</code>" 266 <p> 267 This is the flavor intended to be the final release bits. 268 <ul> 269 <li>Installs modules tagged with <code>user</code>. 270 <li>Installs non-APK modules that have no tags specified. 271 <li>Installs APKs according to the product definition files; tags 272 are ignored for APK modules. 273 <li><code>ro.secure=1</code> 274 <li><code>ro.debuggable=0</code> 275 <li><code>adb</code> is disabled by default. 276 </td> 277</tr> 278<tr> 279 <td> 280 <code>userdebug<code> 281 </td> 282 <td> 283 "<code>make userdebug</code>" 284 <p> 285 The same as <code>user</code>, except: 286 <ul> 287 <li>Also installs modules tagged with <code>debug</code>. 288 <li><code>ro.debuggable=1</code> 289 <li><code>adb</code> is enabled by default. 290 </td> 291</tr> 292</table> 293 294<p> 295If you build one flavor and then want to build another, you should run 296"<code>make installclean</code>" between the two makes to guarantee that 297you don't pick up files installed by the previous flavor. "<code>make 298clean</code>" will also suffice, but it takes a lot longer. 299</p> 300 301 302<h3>More pseudotargets</h3> 303<p>Sometimes you want to just build one thing. The following pseudotargets are 304there for your convenience:</p> 305 306<ul> 307<li><b>droid</b> - <code>make droid</code> is the normal build. This target 308is here because the default target has to have a name.</li> 309<li><b>all</b> - <code>make all</code> builds everything <code>make 310droid</code> does, plus everything whose <code>LOCAL_MODULE_TAGS</code> do not 311include the "droid" tag. The build server runs this to make sure 312that everything that is in the tree and has an Android.mk builds.</li> 313<li><b>clean-$(LOCAL_MODULE)</b> and <b>clean-$(LOCAL_PACKAGE_NAME)</b> - 314Let you selectively clean one target. For example, you can type 315<code>make clean-libutils</code> and it will delete libutils.so and all of the 316intermediate files, or you can type <code>make clean-Home</code> and it will 317clean just the Home app.</li> 318<li><b>clean</b> - <code>make clean</code> deletes all of the output and 319intermediate files for this configuration. This is the same as <code>rm -rf 320out/<configuration>/</code></li> 321<li><b>clobber</b> - <code>make clobber</code> deletes all of the output 322and intermediate files for all configurations. This is the same as 323<code>rm -rf out/</code>.</li> 324<li><b>dataclean</b> - <code>make dataclean</code> deletes contents of the data 325directory inside the current combo directory. This is especially useful on the 326simulator and emulator, where the persistent data remains present between 327builds.</li> 328<li><b>showcommands</b> - <code>showcommands</code> is a modifier target 329which causes the build system to show the actual command lines for the build 330steps, instead of the brief descriptions. Most people don't like seeing the 331actual commands, because they're quite long and hard to read, but if you need 332to for debugging purposes, you can add <code>showcommands</code> to the list 333of targets you build. For example <code>make showcommands</code> will build 334the default android configuration, and <code>make runtime showcommands</code> 335will build just the runtime, and targets that it depends on, while displaying 336the full command lines. Please note that there are a couple places where the 337commands aren't shown here. These are considered bugs, and should be fixed, 338but they're often hard to track down. Please let 339<a href="mailto:android-build-team">android-build-team</a> know if you find 340any.</li> 341<li><b>LOCAL_MODULE</b> - Anything you specify as a <code>LOCAL_MODULE</code> 342in an Android.mk is made into a pseudotarget. For example, <code>make 343runtime</code> might be shorthand for <code>make 344out/linux-x86-debug/system/bin/runtime</code> (which would work), and 345<code>make libkjs</code> might be shorthand for <code>make 346out/linux-x86-debug/system/lib/libkjs.so</code> (which would also work).</li> 347<li><b>targets</b> - <code>make targets</code> will print a list of all of 348the LOCAL_MODULE names you can make.</li> 349</ul> 350 351<h3><a name="templates"/>How to add another component to the build - Android.mk templates</h3> 352<p>You have a new library, a new app, or a new executable. For each of the 353common types of modules, there is a corresponding file in the templates 354directory. It will usually be enough to copy one of these, and fill in your 355own values. Some of the more esoteric values are not included in the 356templates, but are instead just documented here, as is the documentation 357on using custom tools to generate files.</p> 358<p>Mostly, you can just look for the TODO comments in the templates and do 359what it says. Please remember to delete the TODO comments when you're done 360to keep the files clean. The templates have minimal documentation in them, 361because they're going to be copied, and when that gets stale, the copies just 362won't get updated. So read on...</p> 363 364<h4>Apps</h4> 365<p>Use the <code>templates/apps</code> file.</p> 366<p>This template is pretty self-explanitory. See the variables below for more 367details.</p> 368 369<h4>Java Libraries</h4> 370<p>Use the <code>templates/java_library</code> file.</p> 371<p>The interesting thing here is the value of LOCAL_MODULE, which becomes 372the name of the jar file. (Actually right now, we're not making jar files yet, 373just directories of .class files, but the directory is named according to 374what you put in LOCAL_MODULE). This name will be what goes in the 375LOCAL_JAVA_LIBRARIES variable in modules that depend on your java library.</p> 376 377<h4>C/C++ Executables</h4> 378<p>Use the <code>templates/executable</code> file, or the 379<code>templates/executable_host</code> file.</p> 380<p>This template has a couple extra options that you usually don't need. 381Please delete the ones you don't need, and remove the TODO comments. It makes 382the rest of them easier to read, and you can always refer back to the templates 383if you need them again later.</p> 384<p>By default, on the target these are built into /system/bin, and on the 385host, they're built into <combo>/host/bin. These can be overridden by setting 386<code>LOCAL_MODULE_PATH</code>. See 387<a href="#moving-targets">Putting targets elsewhere</a> 388for more.</p> 389 390<h4>Shared Libraries</h4> 391<p>Use the <code>templates/shared_library</code> file, or the 392<code>templates/shared_library_host</code> file.</p> 393<p>Remember that on the target, we use shared libraries, and on the host, 394we use static libraries, since executable size isn't as big an issue, and it 395simplifies distribution in the SDK.</p> 396 397<h4>Static Libraries</h4> 398<p>Use the <code>templates/static_library</code> file, or the 399<code>templates/static_library_host</code> file.</p> 400<p>Remember that on the target, we use shared libraries, and on the host, 401we use static libraries, since executable size isn't as big an issue, and it 402simplifies distribution in the SDK.</p> 403 404<h4><a name="custom-tools"/>Using Custom Tools</h4> 405<p>If you have a tool that generates source files for you, it's possible 406to have the build system get the dependencies correct for it. Here are 407a couple of examples. <code>$@</code> is the make built-in variable for 408"the current target." The <font color=red>red</font> parts are the parts you'll 409need to change.</p> 410 411<p>You need to put this after you have declared <code>LOCAL_PATH</code> and 412<code>LOCAL_MODULE</code>, because the <code>$(local-intermediates-dir)</code> 413and <code>$(local-host-intermediates-dir)</code> macros use these variables 414to determine where to put the files. 415 416<h5>Example 1</h5> 417<p>Here, there is one generated file, called 418chartables.c, which doesn't depend on anything. And is built by the tool 419built to $(HOST_OUT_EXECUTABLES)/dftables. Note on the second to last line 420that a dependency is created on the tool.</p> 421<pre> 422intermediates:= $(local-intermediates-dir) 423GEN := $(intermediates)/<font color=red>chartables.c</font> 424$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>$(HOST_OUT_EXECUTABLES)/dftables $@</font> 425$(GEN): <font color=red>$(HOST_OUT_EXECUTABLES)/dftables</font> 426 $(transform-generated-source) 427LOCAL_GENERATED_SOURCES += $(GEN) 428</pre> 429 430<h5>Example 2</h5> 431<p>Here as a hypothetical example, we use use cat as if it were to transform 432a file. Pretend that it does something useful. Note how we use a 433target-specific variable called PRIVATE_INPUT_FILE to store the name of the 434input file.</p> 435<pre> 436intermediates:= $(local-intermediates-dir) 437GEN := $(intermediates)/<font color=red>file.c</font> 438$(GEN): PRIVATE_INPUT_FILE := $(LOCAL_PATH)/<font color=red>input.file</font> 439$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>cat $(PRIVATE_INPUT_FILE) > $@</font> 440$(GEN): <font color=red>$(LOCAL_PATH)/file.c</font> 441 $(transform-generated-source) 442LOCAL_GENERATED_SOURCES += $(GEN) 443</pre> 444 445<h5>Example 3</h5> 446<p>If you have several files that are all similar in 447name, and use the same tool, you can combine them. (here the *.lut.h files are 448the generated ones, and the *.cpp files are the input files)</p> 449<pre> 450intermediates:= $(local-intermediates-dir) 451GEN := $(addprefix $(intermediates)<font color=red>/kjs/, \ 452 array_object.lut.h \ 453 bool_object.lut.h \</font> 454 ) 455$(GEN): PRIVATE_CUSTOM_TOOL = <font color=red>perl libs/WebKitLib/WebKit/JavaScriptCore/kjs/create_hash_table $< -i > $@</font> 456$(GEN): $(intermediates)/<font color=red>%.lut.h</font> : $(LOCAL_PATH)/<font color=red>%.cpp</font> 457 $(transform-generated-source) 458LOCAL_GENERATED_SOURCES += $(GEN) 459</pre> 460 461<h3><a name="platform-specific"/>Platform specific conditionals</h3> 462<p>Sometimes you need to set flags specifically for different platforms. Here 463is a list of which values the different build-system defined variables will be 464set to and some examples.</p> 465<p>For a device build, <code>TARGET_OS</code> is <code>linux</code> (we're using 466linux!), and <code>TARGET_ARCH</code> is <code>arm</code>.</p> 467<p>For a simulator build, <code>TARGET_OS</code> and <code>TARGET_ARCH</code> 468are set to the same as <code>HOST_OS</code> and <code>HOST_ARCH</code> are 469on your platform. <code>TARGET_PRODUCT</code> is the name of the target 470hardware/product you are building for. The value <code>sim</code> is used 471for the simulator. We haven't thought through the full extent of customization 472that will happen here, but likely there will be additional UI configurations 473specified here as well.</p> 474<table cellspacing=25> 475<tr> 476 <td valign=top align=center> 477 <b>HOST_OS</b><br/> 478 linux<br/> 479 darwin<br/> 480 (cygwin) 481 </td> 482 <td valign=top align=center> 483 <b>HOST_ARCH</b><br/> 484 x86 485 </td> 486 <td valign=top align=center> 487 <b>HOST_BUILD_TYPE</b><br/> 488 release<br/> 489 debug 490 </td> 491</tr> 492<tr> 493 <td valign=top align=center> 494 <b>TARGET_OS</b><br/> 495 linux<br/> 496 darwin<br/> 497 (cygwin) 498 </td> 499 <td valign=top align=center> 500 <b>TARGET_ARCH</b><br/> 501 arm<br/> 502 x86 503 </td> 504 <td valign=top align=center> 505 <b>TARGET_BUILD_TYPE</b><br/> 506 release<br/> 507 debug 508 </td> 509 <td valign=top align=center> 510 <b>TARGET_PRODUCT</b><br/> 511 sim<br/> 512 dream<br/> 513 sooner 514 </td> 515</tr> 516</table> 517 518<h4>TARGET_SIMULATOR</h4> 519<p>If we're building the simulator, as opposed to the arm or emulator builds, 520<code>TARGET_SIMULATOR</code> will be set to <code>true</code>. 521 522<h4>Some Examples</h4> 523<pre>ifeq ($(TARGET_SIMULATOR),true) 524LOCAL_CFLAGS += -DSIMULATOR 525endif 526 527ifeq ($(TARGET_BUILD_TYPE),release) 528LOCAL_CFLAGS += -DNDEBUG=1 529endif 530 531# from libutils 532ifeq ($(TARGET_OS),linux) 533# Use the futex based mutex and condition variable 534# implementation from android-arm because it's shared mem safe 535LOCAL_SRC_FILES += futex_synchro.c 536LOCAL_LDLIBS += -lrt -ldl 537endif 538 539</pre> 540 541 542<h3><a name="moving-modules"/>Putting modules elsewhere</h3> 543<p>If you have modules that normally go somewhere, and you need to have them 544build somewhere else, read this. One use of this is putting files on 545the root filesystem instead of where they normally go in /system. Add these 546lines to your Android.mk:</p> 547<pre> 548LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT_SBIN) 549LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_SBIN_UNSTRIPPED) 550</pre> 551<p>For executables and libraries, you need to also specify a 552<code>LOCAL_UNSTRIPPED_PATH</code> location, because on target builds, we keep 553the unstripped executables so GDB can find the symbols.</code> 554<p>Look in <code>config/envsetup.make</code> for all of the variables defining 555places to build things.</p> 556<p>FYI: If you're installing an executable to /sbin, you probably also want to 557set <code>LOCAL_FORCE_STATIC_EXCUTABLE := true</code> in your Android.mk, which 558will force the linker to only accept static libraries.</p> 559 560 561<h3>Android.mk variables</h3> 562<p>These are the variables that you'll commonly see in Android.mk files, listed 563alphabetically.</p> 564<p>But first, a note on variable naming: 565<ul> 566 <li><b>LOCAL_</b> - These variables are set per-module. They are cleared 567 by the <code>include $(CLEAR_VARS)</code> line, so you can rely on them 568 being empty after including that file. Most of the variables you'll use 569 in most modules are LOCAL_ variables.</li> 570 <li><b>PRIVATE_</b> - These variables are make-target-specific variables. That 571 means they're only usable within the commands for that module. It also 572 means that they're unlikely to change behind your back from modules that 573 are included after yours. This 574 <a href="http://www.gnu.org/software/make/manual/make.html#Target_002dspecific">link to the make documentation</a> 575 describes more about target-specific variables. Please note that there 576 are a couple of these laying around the tree that aren't prefixed with 577 PRIVATE_. It is safe, and they will be fixed as they are discovered. 578 Sorry for the confusion.</li> 579 <li><b>INTERNAL_</b> - These variables are critical to functioning of 580 the build system, so you shouldn't create variables named like this, and 581 you probably shouldn't be messing with these variables in your makefiles. 582 </li> 583 <li><b>HOST_</b> and <b>TARGET_</b> - These contain the directories 584 and definitions that are specific to either the host or the target builds. 585 Do not set variables that start with HOST_ or TARGET_ in your makefiles. 586 </li> 587 <li><b>BUILD_</b> and <b>CLEAR_VARS</b> - These contain the names of 588 well-defined template makefiles to include. Some examples are CLEAR_VARS 589 and BUILD_HOST_PACKAGE.</li> 590 <li>Any other name is fair-game for you to use in your Android.mk. However, 591 remember that this is a non-recursive build system, so it is possible that 592 your variable will be changed by another Android.mk included later, and be 593 different when the commands for your rule / module are executed.</li> 594</ul> 595</p> 596 597<h4>LOCAL_ASSET_FILES</h4> 598<p>In Android.mk files that <code>include $(BUILD_PACKAGE)</code> set this 599to the set of files you want built into your app. Usually:</p> 600<p><code>LOCAL_ASSET_FILES += $(call find-subdir-assets)</code></p> 601<p>This will probably change when we switch to ant for the apps' build 602system.</p> 603 604<h4>LOCAL_CC</h4> 605<p>If you want to use a different C compiler for this module, set LOCAL_CC 606to the path to the compiler. If LOCAL_CC is blank, the appropriate default 607compiler is used.</p> 608 609<h4>LOCAL_CXX</h4> 610<p>If you want to use a different C++ compiler for this module, set LOCAL_CXX 611to the path to the compiler. If LOCAL_CXX is blank, the appropriate default 612compiler is used.</p> 613 614<h4>LOCAL_CFLAGS</h4> 615<p>If you have additional flags to pass into the C or C++ compiler, add 616them here. For example:</p> 617<p><code>LOCAL_CFLAGS += -DLIBUTILS_NATIVE=1</code></p> 618 619<h4>LOCAL_CPPFLAGS</h4> 620<p>If you have additional flags to pass into <i>only</i> the C++ compiler, add 621them here. For example:</p> 622<p><code>LOCAL_CPPFLAGS += -ffriend-injection</code></p> 623<code>LOCAL_CPPFLAGS</code> is guaranteed to be after <code>LOCAL_CFLAGS</code> 624on the compile line, so you can use it to override flags listed in 625<code>LOCAL_CFLAGS</code>. 626 627<h4>LOCAL_CPP_EXTENSION</h4> 628<p>If your C++ files end in something other than "<code>.cpp</code>", 629you can specify the custom extension here. For example:</p> 630<p><code>LOCAL_CPP_EXTENSION := .cc</code></p> 631Note that all C++ files for a given module must have the same 632extension; it is not currently possible to mix different extensions. 633 634<h4>LOCAL_NO_DEFAULT_COMPILER_FLAGS</h4> 635<p>Normally, the compile line for C and C++ files includes global include 636paths and global cflags. If <code>LOCAL_NO_DEFAULT_COMPILER_FLAGS</code> 637is non-empty, none of the default includes or flags will be used when compiling 638C and C++ files in this module. 639<code>LOCAL_C_INCLUDES</code>, <code>LOCAL_CFLAGS</code>, and 640<code>LOCAL_CPPFLAGS</code> will still be used in this case, as will 641any <code>DEBUG_CFLAGS</code> that are defined for the module. 642 643<h4>LOCAL_COPY_HEADERS</h4> 644<p class=warning>This will be going away.</p> 645<p>The set of files to copy to the install include tree. You must also 646supply <code>LOCAL_COPY_HEADERS_TO</code>.</p> 647<p>This is going away because copying headers messes up the error messages, and 648may lead to people editing those headers instead of the correct ones. It also 649makes it easier to do bad layering in the system, which we want to avoid. We 650also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any 651headers.</p> 652 653<h4>LOCAL_COPY_HEADERS_TO</h4> 654<p class=warning>This will be going away.</p> 655<p>The directory within "include" to copy the headers listed in 656<code>LOCAL_COPY_HEADERS</code> to.</p> 657<p>This is going away because copying headers messes up the error messages, and 658may lead to people editing those headers instead of the correct ones. It also 659makes it easier to do bad layering in the system, which we want to avoid. We 660also aren't doing a C/C++ SDK, so there is no ultimate requirement to copy any 661headers.</p> 662 663<h4>LOCAL_C_INCLUDES</h4> 664<p>Additional directories to instruct the C/C++ compilers to look for header 665files in. These paths are rooted at the top of the tree. Use 666<code>LOCAL_PATH</code> if you have subdirectories of your own that you 667want in the include paths. For example:</p> 668<p><code> 669LOCAL_C_INCLUDES += extlibs/zlib-1.2.3<br/> 670LOCAL_C_INCLUDES += $(LOCAL_PATH)/src 671</code></p> 672<p>You should not add subdirectories of include to 673<code>LOCAL_C_INCLUDES</code>, instead you should reference those files 674in the <code>#include</code> statement with their subdirectories. For 675example:</p> 676<p><code>#include <utils/KeyedVector.h></code><br/> 677not <code><s>#include <KeyedVector.h></s></code></p> 678<p>There are some components that are doing this wrong, and should be cleaned 679up.</p> 680 681<h4>LOCAL_MODULE_TAGS</h4> 682<p>Set <code>LOCAL_MODULE_TAGS</code> to any number of whitespace-separated 683tags. If the tag list is empty or contains <code>droid</code>, the module 684will get installed as part of a <code>make droid</code>. Otherwise, it will 685only get installed by running <code>make <your-module></code> 686or with the <code>make all</code> pseudotarget.</p> 687 688<h4>LOCAL_REQUIRED_MODULES</h4> 689<p>Set <code>LOCAL_REQUIRED_MODULES</code> to any number of whitespace-separated 690module names, like "libblah" or "Email". If this module is installed, all 691of the modules that it requires will be installed as well. This can be 692used to, e.g., ensure that necessary shared libraries or providers are 693installed when a given app is installed. 694 695<h4>LOCAL_FORCE_STATIC_EXECUTABLE</h4> 696<p>If your executable should be linked statically, set 697<code>LOCAL_FORCE_STATIC_EXECUTABLE:=true</code>. There is a very short 698list of libraries that we have in static form (currently only libc). This is 699really only used for executables in /sbin on the root filesystem.</p> 700 701<h4>LOCAL_GENERATED_SOURCES</h4> 702<p>Files that you add to <code>LOCAL_GENERATED_SOURCES</code> will be 703automatically generated and then linked in when your module is built. 704See the <a href="#custom-tools">Custom Tools</a> template makefile for an 705example.</p> 706 707<h4>LOCAL_JAVA_LIBRARIES</h4> 708<p>When linking Java apps and libraries, <code>LOCAL_JAVA_LIBRARIES</code> 709specifies which sets of java classes to include. Currently there are 710two of these: <code>core</code> and <code>framework</code>. 711In most cases, it will look like this:</p> 712<p><code>LOCAL_JAVA_LIBRARIES := core framework</code></p> 713<p>Note that setting <code>LOCAL_JAVA_LIBRARIES</code> is not necessary 714(and is not allowed) when building an APK with 715"<code>include $(BUILD_PACKAGE)</code>". The appropriate libraries 716will be included automatically.</p> 717 718<h4>LOCAL_LDFLAGS</h4> 719<p>You can pass additional flags to the linker by setting 720<code>LOCAL_LDFLAGS</code>. Keep in mind that the order of parameters is 721very important to ld, so test whatever you do on all platforms.</p> 722 723<h4>LOCAL_LDLIBS</h4> 724<p><code>LOCAL_LDLIBS</code> allows you to specify additional libraries 725that are not part of the build for your executable or library. Specify 726the libraries you want in -lxxx format; they're passed directly to the 727link line. However, keep in mind that there will be no dependency generated 728for these libraries. It's most useful in simulator builds where you want 729to use a library preinstalled on the host. The linker (ld) is a particularly 730fussy beast, so it's sometimes necessary to pass other flags here if you're 731doing something sneaky. Some examples:</p> 732<p><code>LOCAL_LDLIBS += -lcurses -lpthread<br/> 733LOCAL_LDLIBS += -Wl,-z,origin 734</code></p> 735 736<h4>LOCAL_NO_MANIFEST</h4> 737<p>If your package doesn't have a manifest (AndroidManifest.xml), then 738set <code>LOCAL_NO_MANIFEST:=true</code>. The common resources package 739does this.</p> 740 741<h4>LOCAL_PACKAGE_NAME</h4> 742<p><code>LOCAL_PACKAGE_NAME</code> is the name of an app. For example, 743Dialer, Contacts, etc. This will probably change or go away when we switch 744to an ant-based build system for the apps.</p> 745 746<h4>LOCAL_PATH</h4> 747<p>The directory your Android.mk file is in. You can set it by putting the 748following as the first line in your Android.mk:</p> 749<p><code>LOCAL_PATH := $(my-dir)</code></p> 750<p>The <code>my-dir</code> macro uses the 751<code><a href="http://www.gnu.org/software/make/manual/make.html#MAKEFILE_005fLIST-Variable">MAKEFILE_LIST</a></code> 752variable, so you must call it before you include any other makefiles. Also, 753consider that any subdirectories you inlcude might reset LOCAL_PATH, so do your 754own stuff before you include them. This also means that if you try to write 755several <code>include</code> lines that reference <code>LOCAL_PATH</code>, 756it won't work, because those included makefiles might reset LOCAL_PATH. 757 758<h4>LOCAL_POST_PROCESS_COMMAND</h4> 759<p>For host executables, you can specify a command to run on the module 760after it's been linked. You might have to go through some contortions 761to get variables right because of early or late variable evaluation:</p> 762<p><code>module := $(HOST_OUT_EXECUTABLES)/$(LOCAL_MODULE)<br/> 763LOCAL_POST_PROCESS_COMMAND := /Developer/Tools/Rez -d __DARWIN__ -t APPL\<br/> 764 -d __WXMAC__ -o $(module) Carbon.r 765</code></p> 766 767<h4>LOCAL_PREBUILT_EXECUTABLES</h4> 768<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to 769executables that you want copied. They're located automatically into the 770right bin directory.</p> 771 772<h4>LOCAL_PREBUILT_LIBS</h4> 773<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to 774libraries that you want copied. They're located automatically into the 775right lib directory.</p> 776 777<h4>LOCAL_SHARED_LIBRARIES</h4> 778<p>These are the libraries you directly link against. You don't need to 779pass transitively included libraries. Specify the name without the suffix:</p> 780<p><code>LOCAL_SHARED_LIBRARIES := \<br/> 781 libutils \<br/> 782 libui \<br/> 783 libaudio \<br/> 784 libexpat \<br/> 785 libsgl 786</code></p> 787 788<h4>LOCAL_SRC_FILES</h4> 789<p>The build system looks at <code>LOCAL_SRC_FILES</code> to know what source 790files to compile -- .cpp .c .y .l .java. For lex and yacc files, it knows 791how to correctly do the intermediate .h and .c/.cpp files automatically. If 792the files are in a subdirectory of the one containing the Android.mk, prefix 793them with the directory name:</p> 794<p><code>LOCAL_SRC_FILES := \<br/> 795 file1.cpp \<br/> 796 dir/file2.cpp 797</code></p> 798 799<h4>LOCAL_STATIC_LIBRARIES</h4> 800<p>These are the static libraries that you want to include in your module. 801Mostly, we use shared libraries, but there are a couple of places, like 802executables in sbin and host executables where we use static libraries instead. 803<p><code>LOCAL_STATIC_LIBRARIES := \<br/> 804 libutils \<br/> 805 libtinyxml 806</code></p> 807 808<h4>LOCAL_MODULE</h4> 809<p><code>LOCAL_MODULE</code> is the name of what's supposed to be generated 810from your Android.mk. For exmample, for libkjs, the <code>LOCAL_MODULE</code> 811is "libkjs" (the build system adds the appropriate suffix -- .so .dylib .dll). 812For app modules, use <code>LOCAL_PACKAGE_NAME</code> instead of 813<code>LOCAL_MODULE</code>. We're planning on switching to ant for the apps, 814so this might become moot.</p> 815 816<h4>LOCAL_MODULE_PATH</h4> 817<p>Instructs the build system to put the module somewhere other than what's 818normal for its type. If you override this, make sure you also set 819<code>LOCAL_UNSTRIPPED_PATH</code> if it's an executable or a shared library 820so the unstripped binary has somewhere to go. An error will occur if you forget 821to.</p> 822<p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 823 824<h4>LOCAL_UNSTRIPPED_PATH</h4> 825<p>Instructs the build system to put the unstripped version of the module 826somewhere other than what's normal for its type. Usually, you override this 827because you overrode <code>LOCAL_MODULE_PATH</code> for an executable or a 828shared library. If you overrode <code>LOCAL_MODULE_PATH</code>, but not 829<code>LOCAL_UNSTRIPPED_PATH</code>, an error will occur.</p> 830<p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p> 831 832<h4>LOCAL_WHOLE_STATIC_LIBRARIES</h4> 833<p>These are the static libraries that you want to include in your module without allowing 834the linker to remove dead code from them. This is mostly useful if you want to add a static library 835to a shared library and have the static library's content exposed from the shared library. 836<p><code>LOCAL_WHOLE_STATIC_LIBRARIES := \<br/> 837 libsqlite3_android<br/> 838</code></p> 839 840<h4>LOCAL_YACCFLAGS</h4> 841<p>Any flags to pass to invocations of yacc for your module. A known limitation 842here is that the flags will be the same for all invocations of YACC for your 843module. This can be fixed. If you ever need it to be, just ask.</p> 844<p><code>LOCAL_YACCFLAGS := -p kjsyy</code></p> 845 846 847 848<h2>Implementation Details</h2> 849 850<p>You should never have to touch anything in the config directory unless 851you're adding a new platform, new tools, or adding new features to the 852build system. In general, please consult with the build system owner(s) 853(<a href="mailto:android-build-team">android-build-team</a>) before you go 854mucking around in here. That said, here are some notes on what's going on 855under the hood.</p> 856 857<h3>Environment Setup / buildspec.mk Versioning</h3> 858<p>In order to make easier for people when the build system changes, when 859it is necessary to make changes to buildspec.mk or to rerun the environment 860setup scripts, they contain a version number in the variable 861BUILD_ENV_SEQUENCE_NUMBER. If this variable does not match what the build 862system expects, it fails printing an error message explaining what happened. 863If you make a change that requires an update, you need to update two places 864so this message will be printed. 865<ul> 866 <li>In config/envsetup.make, increment the 867 CORRECT_BUILD_ENV_SEQUENCE_NUMBER definition.</li> 868 <li>In buildspec.mk.default, update the BUILD_ENV_SEQUENCE_DUMBER 869 definition to match the one in config/envsetup.make</li> 870</ul> 871The scripts automatically get the value from the build system, so they will 872trigger the warning as well. 873</p> 874 875<h3>Additional makefile variables</h3> 876<p>You probably shouldn't use these variables. Please consult 877<a href="mailto:android-build-team">android-build-team</a> before using them. 878These are mostly there for workarounds for other issues, or things that aren't 879completely done right.</p> 880 881<h4>LOCAL_ADDITIONAL_DEPENDENCIES</h4> 882<p>If your module needs to depend on anything else that 883isn't actually built in to it, you can add those make targets to 884<code>LOCAL_ADDITIONAL_DEPENDENCIES</code>. Usually this is a workaround 885for some other dependency that isn't created automatically.</p> 886 887<h4>LOCAL_BUILT_MODULE</h4> 888<p>When a module is built, the module is created in an intermediate 889directory then copied to its final location. LOCAL_BUILT_MODULE is 890the full path to the intermediate file. See LOCAL_INSTALLED_MODULE 891for the path to the final installed location of the module.</p> 892 893<h4>LOCAL_HOST</h4> 894<p>Set by the host_xxx.make includes to tell base_rules.make and the other 895includes that we're building for the host. Kenneth did this as part of 896openbinder, and I would like to clean it up so the rules, includes and 897definitions aren't duplicated for host and target.</p> 898 899<h4>LOCAL_INSTALLED_MODULE</h4> 900<p>The fully qualified path name of the final location of the module. 901See LOCAL_BUILT_MODULE for the location of the intermediate file that 902the make rules should actually be constructing.</p> 903 904<h4>LOCAL_REPLACE_VARS</h4> 905<p>Used in some stuff remaining from the openbinder for building scripts 906with particular values set,</p> 907 908<h4>LOCAL_SCRIPTS</h4> 909<p>Used in some stuff remaining from the openbinder build system that we 910might find handy some day.</p> 911 912<h4>LOCAL_MODULE_CLASS</h4> 913<p>Which kind of module this is. This variable is used to construct other 914variable names used to locate the modules. See base_rules.make and 915envsetup.make.</p> 916 917<h4>LOCAL_MODULE_NAME</h4> 918<p>Set to the leaf name of the LOCAL_BUILT_MODULE. I'm not sure, 919but it looks like it's just used in the WHO_AM_I variable to identify 920in the pretty printing what's being built.</p> 921 922<h4>LOCAL_MODULE_SUFFIX</h4> 923<p>The suffix that will be appended to <code>LOCAL_MODULE</code> to form 924<code>LOCAL_MODULE_NAME</code>. For example, .so, .a, .dylib.</p> 925 926<h4>LOCAL_STRIP_MODULE</h4> 927<p>Calculated in base_rules.make to determine if this module should actually 928be stripped or not, based on whether <code>LOCAL_STRIPPABLE_MODULE</code> 929is set, and whether the combo is configured to ever strip modules. With 930Iliyan's stripping tool, this might change.</p> 931 932<h4>LOCAL_STRIPPABLE_MODULE</h4> 933<p>Set by the include makefiles if that type of module is strippable. 934Executables and shared libraries are.</p> 935 936<h4>LOCAL_SYSTEM_SHARED_LIBRARIES</h4> 937<p>Used while building the base libraries: libc, libm, libdl. Usually 938it should be set to "none," as it is in $(CLEAR_VARS). When building 939these libraries, it's set to the ones they link against. For example, 940libc, libstdc++ and libdl don't link against anything, and libm links against 941libc. Normally, when the value is none, these libraries are automatically 942linked in to executables and libraries, so you don't need to specify them 943manually.</p> 944 945 946</body> 947</html> 948